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[Junos] How to mount a USB drive on the EX/SRX/MX/QFX series platforms



Article ID: KB12880 KB Last Updated: 14 Oct 2020Version: 11.0

This article explains how to mount a USB drive on an EX/SRX/MX/QFX series device and copy files to or from the device via the USB drive.


The following procedure allow users to mount a USB device on EX/SRX/MX/QFX devices.  This can be helpful if network connectivity is unavailable and you need to copy files to or from the device.

Note: It is recommended to have USB with FAT32 format.

  1. Enter the shell as root:

    user@switch> start shell user root
  2. Before inserting the USB device, perform the following:

    root@% ls /dev/da*
    /dev/da0 /dev/da0s1c /dev/da0s2a /dev/da0s3 /dev/da0s3e
    /dev/da0s1 /dev/da0s1f /dev/da0s2c /dev/da0s3c
    /dev/da0s1a /dev/da0s2 /dev/da0s2f /dev/da0s3d
  3. Insert the USB drive in the USB port. The following output will be displayed:

    root@% umass1: TOSHIBA TransMemory, rev 2.00/1.00, addr 3
    da2 at umass-sim1 bus 1 target 0 lun 0
    da2: <TOSHIBA TransMemory 5.00> Removable Direct Access SCSI-0 device 
    da2: 40.000MB/s transfers
    da2: 983MB (2013184 512 byte sectors: 64H 32S/T 983C)
    root@% ls /dev/da*
    /dev/da0 /dev/da0s1c /dev/da0s2a /dev/da0s3 /dev/da0s3e
    /dev/da0s1 /dev/da0s1f /dev/da0s2c /dev/da0s3c /dev/da2
    /dev/da0s1a /dev/da0s2 /dev/da0s2f /dev/da0s3d /dev/da2s1
    Note: '/dev/da2s1' is the USB drive.  If the console session is not available while inserting the USB, check the var log file names "messages" for logs related to "da"(e.g. show log messages | match da). It will log the same 4 lines as is shown on console if it is plugged live.
  4. Create a directory for the USB drive to mount to:

    root@% mkdir /var/tmp/usb
  5. . Mount the USB drive to the /var/tmp/usb directory:

    root@% mount_msdosfs /dev/da2s1 /var/tmp/usb
    root@% ls /var/tmp/usb
    Note: 'ls /var/tmp/usb' will show all the files in the USB drive.
  6. For QFX use the following command to mount

    root@% mount -t msdos /dev/da2s1 /var/tmp/usb
    root@% ls /var/tmp/usb
  7.  Copy any of the USB files to the /var/tmp/usb directory:

    root@% cp /var/tmp/usb/images.tgz /var/tmp
    root@% ls /var/tmp
    The images.tgz file from the USB is successfully copied to the /var/tmp directory.
  8. Now unmount the USB drive after the file is completely copied:

    root@% umount /var/tmp/usb
    root@% umass1: at uhub0 port 1 (addr 3) disconnected
    (da1:umass-sim1:1:0:0): lost device
    (da1:umass-sim1:1:0:0): removing device entry
    umass1: detached

    Note:  ‚ÄčEnsure that the USB devices are unmounted properly before removing them from the router. For devices with multiple USBs, make sure that you unmount both devices.

Modification History:

2020-02-06: Added a note in Step 3 to check the var log file names
2020-01-27: Removed references to J-Series devices and added mount command for QFX.
2019-11-30: Added related PRs.
2017-12-1: Added note to step 7 regarding devices with multiple USBs.

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